Pavement laying apparatus



ugf- 23, 1966 y M. l. HUDIS 3,26%624 PAVEMENT LAYING APPARATUS Filed May 22, 1963 5 Sheets-Sheet 1 A Yigg/V1 A s.

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Aug. 23, 1966 M. l. Hunls PAVEMENT LAYING APPARATUS 5 Sheets-Sheet 2 Filed May 22, 1965 INVENTOR- MICHAEL l. Hums BY n Aug. 23, 1966 M. l. HUDIS 3,267,324

PAVEMENT LAYING APPARATUS Filed May 22, 1963 5 Sheets-Sheet 5 FIG 6.

e INVENTOR.

MICHAEL l. m Hunls h Aug. 23, 1966 Filed May 22, 196s M. l. HUDIS PAVEMENT LAYING APPARATUS |93 lea 5,/ Isa 5 Sheets-Sheet 4 INVENTOR. MICHAEL l. HUDIS Bywmw Aug- 23, 1966 M. l. HuDls 3,267,824

PAVEMENT LAY ING APPARATUS Filed May 22, 1963 5 Sheets-Sheet 5 INVENTORIS MlcHAEl. |.Huo mls-@l United States Patent O 3,267,824 PAVEMENT LAYING APPARATUS Michael I. Hudis, Brookfield, Wis., assignor to Rex Chanbelt Inc., a corporation of Wisconsin Filed May 22, 1963, Ser. No. 282,295 8 Claims. (Cl. 94-46) This invention relates generally to pavement laying apparatus and more particularly to new and improved arrangements for expeditiously and uniformly distributing and placing paving material in plastic condition upon a site to form a homogeneous monolithic slab of pavement.

In the placing of paving material such for example as freshly mixed concrete in plastic condition to form a slab of pavement, it is highly desirable that the plastic material be distributed throughout the full breadth of the slab site as expeditiously as possible and with a minimum of disturbance to the intermixed constituent material-s. Furthermore, it is required that the material be distributed in a uniform manner to avoid unequal compaction upon the base and it is preferable that the equip- -ment used be capable of moving rather large quantities of the plastic material rapidly and smoothly to its final position in forming the slab thereby to expedite the work. Since hauling vehicles ordinarily used to transport freshly mixed concrete carry heavy loads and operate on close schedules, it is desirable that the plac-ing equipment be capable of receiving and rapidly placing a large volume of the material as fast as it can be discharged from successive vehicles thereby to avoid sustaining at any time the concentrated load of a large mass of material at one side of the machine which might otherwise be injur-ions either to the machine or to the supporting trackway form.

It is accordingly, a general object of the present invention to provide improved apparatus for distributing and placing paving material in plastic condition to form a sla-b of pavement.

An-other object ofthe invention is to provide an improved paving material placer that is adapted to accept a full load of freshly mixed concrete poured rapidly from a parked transportation vehicle while simultaneously distributing the concerte expeditiously across the site being paved.

Another object is to provide an improved paving material distributor including a conveyor screw operating .in a transverse distributing box, that is adapted to receive plastic paving material in large quantities and to place it rapidly and uniformly in position to form a pavement slab.

Another object is to provide an improved pavement laying machine that is adapted to receive and to transport a heavy load of plastic paving material with the weight of the material so distributed as to avoid exerting excessive forces upon the machine or the supporting trackway structure.

Another object is to provide an improved pavement material placing apparatus that is arranged to receive a full load of the material from a parked hauling vehicle while the apparatus is traveling forward in distributing the load of material upon the slab site.

Another object is to provide an improved pavement laying machine whereby the paving material is applied evenly and continuously upon the site being paved in a manner to avoid uneven compaction of the material on the base.

Another object is to provide improved mesh laying equipment for positioning reinforcing mesh within a monolithic slab of pavement being laid.

"ice

Another object is to provide an improved pavement laying method in which the plastic paving material is poured through the reinforcing mesh to embed it and the mesh then is positioned within the material at the required depth.

Another object is to provide an improved pavement laying machine of the slip-form type in which plastic paving material is distributed transversely of the machine between the slip forms by a screw conveyor operating within a spreading trough.

According to the present invention, paving material in plastic condition such as freshly mixed concrete may be handled in large quantities expeditiously distributed across and placed uniformly in its nal position upon a prepared base in the form of a broad ribbon or strip that constitutes a pavement slab. This rapid distribution is accomplished by means of improved placing apparatus including a large trough or box constituting a reservoir for plastic concrete that extends transversely of the slab site and that opens along the bottom under operator control to discharge the concrete onto the base as the apparatus moves forward. Within the transverse reservoir or trough there is provided a conveyor constituted by two transfer screws arranged end to end and individually operated for distributing the material transversely along the trough. The apparatus is arranged to receive and distri-bute plastic concrete as rapidly as it can be delivered to the site by the usual hauling equipment ordinarily employed for that purpose. This expeditious placing of the material is facilitated by auxiliary feeder units that extend forwardly from each end of the transverse trough. Each feeder unit is of such length and capacity that the full load of a parked hauling vehicle may be dumped into it as the placing machine advances without requiring movement of the vehicle from its Ispotted position. Each of the feeder units i-s in the form of a trough that houses a longitudinal feeder screw conveyor which feeds the material into the adjacent end of the transverse distributing trough. The feeding and distributing screws are of sufficient capacity to move the material as rapidly as it pours into the feeding trough from the hauling vehicle whereby the material is transferred quickly into the transverse trough and promptly lows down onto the base at it is being distributed transversely by the distributing screws. In this manner, much of the weight of the material is transferred at once to the slab base while in the course of being distributed transversely across the base by the machine. By this arrangement the weight of a full load of heavy concrete is never allowed to be concentrated on one side of the machine and the one line for-ms that support it. Furthermore, the weight of the material that is being distributed transversely within the machine is likewise distributed longitudinally of the supporting forms by an equalizing arrangement of the several wheels that support the machine on the forms. In distributing the material, the conveyor screws operate also to remix and unify the concrete as it is dumped from the hauling vehicle. Furthermore, as the material is spread transversely, it may be maintained at a substantially uniform depth throughout the width of the slab being formed and therefore is evenly compacted in a manner to promote uniform solidification of the pavement. An adjustable strike-olf apparatus operates to limit the rate of flow of the material rearwardly from the trough opening and serves to extrude the pavement slab to the desired thickness and contour as the machine advances along the forms. A separate hydraulic motor is utilized to drive each of the feeding screws and each of the aligned distributing screws the motors all being alike and interchangeable. The motors are provided with control apparatus whereby 3 each screw may be operated in either direction selectively and independently as may be required in trans-ferring and placing the material. Preferably, a separate hydraulic pump is provided for supplying each motor independently, the several pumps likewise being interchangeable. The machine may be fitted at the rear with the usual transverse screed to smooth the slab surface or the entire placer unit may be incorporated as the forward part of a combined spreading and finishing machine either of the type adapted for operating on forms or of the slip-form type. Furthermore, mesh placing equipment may be provided within the placer unit whereby the concrete flowing from the trough opening pouns down through the mesh while held in an elevated position after which the mesh i-s forced downward to .its precise final position in the sla-b.

The foregoing and other objects of this invention will become more readily apparent upon perusing the following detailed description of embodying apparatus in conjunction with its representation in the accompanying drawing that shows an improved pavement laying machine and modifications thereof illu-strative of the invention in its presently modified form, wherein: v

FIGURE l is a view in perspective of an improved pavement material placing machine embodying the invention and shown mounted in operating position upon spaced side forms that define the s-ite of the pavement slab being laid;

FIG. 2 is a diagrammatic plan View of the improved pavement laying machine shown in FIG. 1, with much of the operating mechanism being indicated schematically;

FIG. 3 is an enlarged fragmentary View in left side elevation of the forward or placing unit of the pavement laying machine shown in FIGS. l and 2, part of the propelling power unit having been broken away;

FIG. 4 is a view in longitudinal section through the transverse distributing box of the placing machine, taken on the vertical plane represented bythe line 4-4 in FIG. 6;

FIG. 5 is another view in vertical longitudinal section generally similar to FIG. 4 but taken on another plane represented by the line 5--5 in FIG. 6 and showing in broken lines the manner in which the clamshell distributing box opens to discharge material;

FIG. 6 is an enlarged fragmentary view of the left half of the transverse distributing box, partly in rear elevation and partly in transverse section, taken on the plane represented by the line `6 6 in FIG. 3, with parts broken away to show internal structure;

FIG. 7 is a View in left side elevation on a reduced scale of a combined pavement laying and linishing machine in which the apparatus embodying the invention is incorporated as the forward part;

FIG. 8 is a View somewhat similar to FIG. 7 but showing the placing machine of this invention incorporated as the forward part of a paver of the slip-form type;

FIG. 9 is another vie-W generally similar to FIGS. 7 and 8 but showing a modified slip-form paver with the material placing apparatus of this invention integrated into it;

FIG. 10 is a partly diagrammatic View in vertical longitudinal section through the distributing box, generally similar to FIG. 5 but showing in addition improved mesh placing apparatus that may be used in conjunction with the placing machine, the view being taken on the plane represented by the line 10-10 in FIG. 11;

FIG. 1l is a fragmentary plan view of the right side Vpart of the placing kmachine equipped with lthe mesh placer shown in section in FIG. 10;

FIG. 12 is a fragmentary View in perspective of the left side part of the placing machine showing a modified form of feeder hopper extending laterally therefrom; and,

lFIG. 13 is a view in transverse section through one of the other longitudinally disposed feeder hoppers and its supporting bogie, taken on the vertical plane represented by the line 13-13 in FIG. 3.

The particular improved pavement slab laying machine that is shown in the drawing as the principal embodiment illustrative of the present invention, is especially adapted for distributing and placing large quantities of paving material in plastic condition such as freshly mixed concrete upon the site of a pavement slab being laid. By means of `this machine, the freshly mixed concrete or other plastic paving material may be received from either or both sides of the slab site alternately or simultaneously as rapidly as it can be delivered by and discharged from any of the usual material hauling or mixing equipment now in general use in the paving of highways, airport landing strips and the like. As fast as the material is received at the placing machine of the invention, it is distributed and placed expeditiously and uniformly upon the slab site in the form of a molded continuous ribbon or slab of pavement.

This rapid placement of the paving material is accomplished by means of a large transverse conveyor constituted by aligned transfer screws operating within a trough-like box or hopper of clamshell construction that spans the pavement site and is normally open at the bottom to deposit the material upon the ground in a uniform, equally compaced layer without exerting concentrated loads upon the machine as it advances along the site.

As appears in the drawing, according to one wellknown method of laying pavement, temporary forms F are laid on the ground in spaced parallel relationship along the sides of a prepared sub-base B constituting the site of a pavement slab S being laid. The forms F define and shape the respective edges of the pavement slab S and are positioned and levelled in such manner that their top surfaces serve as guides to establish the elevation of the top surface of the finished slab. The tops of the levelled forms F serve also as trackways or rails for supporting and positioning whatever machinery may be operated along the site to distribute the paving material and to finish the tratiic supporting surface of the slab S to the desired contour at the required elevation.

Referring now more specically to the drawing and particularly to FIGS. 1 and 2 thereof, the improved pavement laying machine there illustrated as the principal exemplifying embodiment, represents the presently preferred and best mode contemplated for practicing the invention. As shown in the drawing, the improved pavement laying machine is adapted to. operate along the forms F as a supporting and guiding trackway and comprises essentially a long open distributing box or placing hopper 20 of trough-like construction that forms a reservoir extending transversely of the sub-base B between the forms F. The transverse distributing hopper 20 is arranged to be opened selectively along the bottom under the control of the machine operator to the extent required to discharge the plastic paving material, such as newly mixed concre-te C, upon the sub-base B in the form of a continuous ribbon as the machine advances along the forms F in laying a pavement slab S of the desired thickness. I

Within the trough 2t), the transverse conveyor is constituted by two large distributing screws or transfer augers 21 and 22 arranged in axial alignment to distribute the material transversely of the slab site. The two screws 21 and 22 are preferably about -twenty-four inches in diameter and they are driven at about fifty-five revolutions a minute by independent hydraulic motors 23 and 24, respectively, mounted at the opposite ends of the box 20. By this arrangement, each of the two screws may be loperate-d independently in either direction of rotation selectively. under the control of the machine operator for transferring and distributing the plastic concrete C across each half respectively of the sub-base B as may be required to maintain a substantially uniform depth of the concrete being fed onto the base.

The transverse distributing box or hopper 20 is supported at each end upon the respective spaced forms F by means of a spring mounted flanged track wheel 25. Along its rear edge, the hopper 20 is provided with an adjustable strike-off mechanism 26 that serves both to regulate the rate of discharge of material from the hopper as the machine advances and to establish the thickness of the slab S. Furthermore, the strike-off 26 may be adjusted to smooth and shape the top surface of the slab Sto a required crowned contour.

In order that successive loads of plastic concrete may be received from hauling vehicles expeditiously and more or less continuously, the transverse hopper 20 has connected to its respective ends forwardly extending longitrudinal feeding or receiving hoppers 27 and 28 disposed parallel with and above the respective side forms F. The two feeding or -charging hoppers 27 and 28 are each about ltwelve feet long and each is supported upon the associated form F by a bogie truck 29 spaced forwardly of the corresponding .spring mounted track wheel 25. To strengthen the structure, the two parallel feeding hoppers are interconnected by a transverse tie rod 30.

Within the respective feeding hoppers 27 and 28, longitudinally disposed transfer augers or feeding screws 31 and 32 are provided for feeding the concrete C rearwardly into the associated' outer ends of the transverse hopper 20 for distribution therealong by the transverse screws 21 and 22. As indicated in the drawing, the feeding screws 31 and 32 are driven individually by hydraulic motors 33 and 34, each being -controlled independently by the machine operator. By this arrangement, the plastic concrete C may be delivered to either or both sides of the sub-base B to be received in either or both of the feeding hoppers 27 and 28, as -the occasion may require, for feeding into the transverse distributing hopper 20.

The longitudinal feeding screws 31 and 32 are somewhat smaller than the transverse screws 21 and 22 being -in this instance about `twenty inches in diameter and they operate somewhat faster preferably being driven at about seventy revolutions a minute. T-heir capacity is sufficient to move the plastic material rapidly into the open transverse hopper 20 as fast as it is poured into the feeding hoppers 27 and 28 from the transport vehicles.

The material handling capacity of the cooperating hoppers and screws is such that when a full load of plastic concrete C is being poured rapidly into the one or the other of the feeding hoppers, the material is carried away by the screws almost as rapidly as it is received and is expeditiously deposited on the slab base B throughout the full length of the open hopper 2t). By this rapid transfer of the material, much of the weight of the concrete C being received is transferred quickly to the subbase B since it is flowing down through the discharge opening while it is being distributed along the hopper 20. Furthermore, the portion of the concrete that is supported by the machine is so distributed along that its Weight is divided between and sustained by both of the supporting side forms F.

Accordingly, when a full load of up to eight cubic yards of plastic concrete is poured from a hauling vehicle into one of the feeding boxes 27 or 28 at a rapid rate, the material is distributed so quickly that by the time the last of the load is received in the charging hopper much of the rst par-t of the load has already been placed upon the sub-base B. Consequently, the full weight of a load of concrete is never imposed solely upon one side of machine and upon the one side form F that supports it. Furthermore, since the concrete being distributed along the transverse trough 20 is supported to a large extent directly upon the sub-base B, the machine never sustains the weight of a full load of concrete because it is continuously being relieved of the weight of the part of 6 the load that is flowing onto and supported by Athe subbase B.

Although the bottom of the transverse box 20 is normally open in order to discharge the plastic concrete as rapidly as it flows into the ends of the box, under some circumstances it may become desirable to close the bottom of the distributing box and then load the machine with the concrete C for hauling it along Ithe forms F. This arrangement may be convenient when it is necessary to place the plastic concrete C in some relatively inaccessible position such as in laying a slab beneath an overhead bridge or out on ythe deck of a narrow bridge where hauling trucks cannot very well be operated.

When using the machine in this manner, the closed transverse box 20 may be filled from end to end with the plastic concrete and, if desired, the two feeding hoppers may be filled also. The entire machine with its load of up to eight or so cubic yards of concrete may then be moved along the forms F to the position of placement, whereupon the bottom of the box may be opened the required amount and the concrete discharged in the usual way as a ribbon slab while advancing the machine along the forms over the area being paved. This process then may be repeated as often as necessary until the paving operation passes the otherwise inaccessible position whereupon the continuous placing operation may be resumed with the concrete being laid as rapidly as it can be delivered to the machine and charged into the feeding troughs.

As may best be seen in FIGS. l, 2 and 3, the improved pavement laying apparatus is formed in two distinct and separable sections or units, a forward or distributing section 38 and a rear propelling section or power unit 40 that are detachably connected together. The distributing section 38 is constituted by the transverse distributing hopper 20 together with the attached longitudinal feeding hoppers 27 and 28 and is supported by the spring mounted wheels 25 and the bogie trucks 29. The cooperating propelling section 40 may assume various forms and in the particular yarrangement shown is generally similar to a conventional concrete spreading machine except that it does not have the usual spreader screw and strike-olf apparatus which in this combined machine are provided by the forward distributing section 38.

As shown in the drawing, both the forward section 38 and the propelling section 40 are of the extensible `type arranged to permit adjusting the width of the combined machine for operating along the forms of varying spacings within limits of the machine adjustment. The particular machine illustrated in FIG. l of the drawing is designed for use in laying pavements from twenty feet to twenty-six feet in width while another model of this machine is adjustable to pavement slab widths varying between twelve feet and eighteen and one-half feet. Obviously, machines having other ranges of adjustment may be provided as required by suitably proportioning the various transverse members and other parts of the rnachine units.

The power unit 40 comprises a rectangular transverse frame 41 that is supported upon the forms F at its respective corners -by flanged traction wheels 42 in the usual manner to constitute a four-wheeled vehicle capable of independent operation along the supporting forms F. The frame 41 of the power unit 40 carries a driving engine 43 that is preferably of the internal combustion type and that is arranged to provide power for propelling and operating the entire machine. The engine 43 is operatively connected by power transmission mechanism 44 of conventional construction to drive the four traction wheels 42 in a manner to move the combined machine along the forms F selectively in either direction at a desired speed.

Means also are provided whereby the engine 43 operates to drive in addition the two spring mounted Wheels 25 at the respective ends of the transverse box 2t). This is accomplished as best shown in FIG. 3 by providing n each of the spring mounted wheels 25 a sprocket wheel 45 that is operatively connected by a power transmission chain 46 to be driven by a sprocket wheel 47 ou the adjacent forward traction wheels 42 of the power unit 4). By this arrangement, each side of the combined machine is provided with three traction wheels which serve to propel the machine along the forms F and that support it in cooperation with the -two wheels of the forward bogie truck 29 thereby making a total of ve wheels arranged in spaced relationship along each side of the machine.

The power unit 40 may if desired be provided at the rear with an adjustable outboard transverse-ly reciprocating screed 49 that operates in the well-known manner of the usual finishing machine screed for smoothing and finishing the upper surface of the newly laid slab S to the required contour as the machine travels along the forms F. Power for driving the reciprocating screed 49 is derived from the engine 43 through the usual screed driving mechanism in a well-known manner. The engine 43 also furnishes the power for operating the hydraulic motors that drive the feeding screws and the distributing screws as well as the power to provide hydrauli'c pressure for actuating various other hydraulic operating and control mechanisms on the machine. A centrally located operators station is provided on the power unit 40 including a control console 51 from which the operator of the machine has control of the various power driven elements of the apparatus.

As appears in the drawing, the arrangement whereby the propulsion section or power unit 40 is mechanically connected to the forward section or distributing unit 33 to push it along the forms F includes a pair of pusher arms or shafts 53 and 54 that are secured to and constitute rearwardly extending elements of the respective feeding hopper structures 27 and 28. As shown in FIG. 2, the arms 53 and 54 are disposed substantially above the forms F and extend rearwardly over and beyond the respective ends of the transverse box to terminate above the end members of the frame 41 of `the power unit 40'. Each of the pusher arms 53 and 54 is provided at its distal end with a vertically extending opening or socket 55 that tits loosely over an upwardly projecting pin or post 56 rigidly fixed on the associated end member of the power unit frame 41.

The posts 56 at the respective ends of the frame 41 constitute king pins that are pivotally received and loosely fitted in the sockets 55 of the arms 53 and 54 in such a manner that when the power unit 40 advances along the (forms F the distributing unit 38 is pushed ahead of it. The cooperating loosely fitted pins and brackets provide a loose jointed lost motion connection between the two units that has a limited degree of flexibility to permit each unit to adjust itself to the forms F being traversed.

Furthermore, these pin and socket connections provide a convenient arrangement whereby the forward unit 38 may be disconnected readily fro-m the pusher unit 40. Thus by simply lifting .the forward unit to disengage sockets 55 of the arms 53 and 54 from the king pins 56 and then disengaging the chains 46 and the other power lines, the two units may be disconnected for separate transportation. When thus disconnected, the power unit 40 is self-sustaining through engagement of its four flanged Wheels 42 with the forms F and likewise the distributing unit is supported by its wheels and bogie units 29 for independent movement along the forms. When separated in this manner, the two units may be lifted from the forms for separate transportation to another pavement laying site for instance, the distributing section 38 being preferably taken apart by removing the feeding hoppers 27 and 28 from the transverse hopper Ztl to facilitate loading for transportation.

As best shown in FIG. 3, each of the spring mounted driven wheels 25 that support the distributing unit 3S near the ends of the transverse hopper 26, is rotatably journalled in Ia movable `wheel housing 61 that is pivotally connected at its forward end by a pivot pin 63 to a bracket 62 that is secured to and projects rearwardly from a part of the adjacent feeding hopper that forms a continuation of each end of the distributing box 20. At its other or rearward end, each wheel housing 61 is pivotally connected to the lower end o-f a resilient compression spring strut 64 the upper end of which is pivotally connected to the lower side of the associated pushing arm 53 or 54. By reason of this resilient .supporting arrangement in the region of each end of the distributing box 20, the maximum load that can be exerted upon the supporting forms F by each wheel 25 is limited to the force exerted by the resilient strut 64. In the particular machine shown, the resilient strut 64 is designed to sustain approximately ve thousand pounds and any load in excess of that amount causes the strut to compress to the extent that the pushing arms 53 and 54 bear down upon the end members of the pushing unit frame 41 thereby transferring part of the load to the pushing unit wheels 42 which act in tandem as bogie trucks to further distribute the load along the forms F.

The yfonward bogie trucks 29 that support the respective longitudinal feeding hoppers 27 and 2S are each provided at each end with .a flanged wheel 67 the two wheels of each bogie fitting upon the forms F in tandem relationship. As shown in FIGS. 1 and 3, the two flanged wheels 67 of each bogie truck are journalled in the respective ends of a longitudinal equalizing truck frame 68 which is pivotally mounted at its mid .point upon a pivot pin 69. Each pivot pin 69 is carried at the lower end of a strut member 70 one o-f which depends from each of .the two feeding hoppers 27 and 28. By reason of the pivoted equalizing frame 68, the load imposed by each feeder unit is distributed substantially equally between the forward and rear wheels 67 of each :bogie truck and is thereby imposed upon the forms F at spaced position some distance from the other wheels 25 and 42.

As may be seen best in FIG. 13, each bogie truck wheel 67 is rotatably mounted on a supporting axle 71 that extends through and is xed in the end of the associated bogie frame 68. The wheels 67 are mounted loosely on the respective axles 71 in a manner `to provide for limited endwise oating movement thereby to accommodate minor sidewise movements of the feeding hoppers relative to the forms F that may occur for instance when negotiating a curved section of the slab lsite defined by the forms.

By this arrangement, the ve separate wheels that support each side of the combined machine upon the corresponding form F are spaced along the form Vfrom end to end of the machine as best shown in FIG. l in a manner adapted to distribute the weight of the machine and its load of concrete over a considerable length of the supporting form structure. Furthermore, the bogie and spring mounted arrangements for the several wheels are adapted to equalize the loads between the various wheels .in such manner that a heavy load of concrete may be carried by the machine without imposing excessive individual wheel loads upon the forms F.

As previously mentioned, three of the five wheels on each side of the machine a-re traction wheels driven by the engine 43, steering clutches and brakes being provided in the driving mechanism 44 in a well-known manner in order that the wheels on either side of the machine may be stopped momentarily while the wheels on the other side continue to rotate thereby enabling the operator to steer the machine for correcting its alignment upon the forms F whenever that may become necessary. A1- `though flanged wheels are shown in the drawing, it is to be understood that they may be replaced by rubber tired wheels or the like for use under special circumstances.

In order to prevent plastic concrete descending from the hopper from being deposited upon or flowing over the tops of the forms F thereby interfering with the wheels, there is provided just ahead of each spring mounted wheel 2S, a form shoe or shield 75 that is resiliently supported by spaced spring arms 76 beneath each of the feeding hoppers 27 and 28 in position to slide along the top of the form F The propulsion engine 43 provides power for driving the feeding and transverse screws by means of a hydraulic transmission system that is indicated schematically in simplified form in FIG. 2 of the drawing. As previously mentioned, the two distributing screws 21 and 22 are driven by the hydraulic motors 23 and 24 at the respective ends of the transverse trough 20. Likewise the two feeding screws 31 and 32 are driven by the hydraulic motors 33 and 34, respectively, mounted at the forward ends of the feeding troughs 27 and 28 The four hydraulic motors 23, 24, 33 and 34 are identical and interchangeable and each is connected by means of a speed reducing mechanism 78 to drive a sprocket 79. From the sprocket 79 a chain 81 transmits power at reduced speed to a large sprocket 82 operatively connected to the end of the associated screw. Pressure fluid for operating each of the motors is supplied from a separate pump, the four pumps likewise being identical and interchangeable and all being driven by the engine 43.

As shown in FIG. 2, a belt drive 84 connects the engine 43 to a jack shaft 84. At the left end of the jack shaft, as viewed in FIG. 2, a gear box S6 is provided and this is connected to and drives a group of three pumps 87 that are shown as connected respectively to drive the motors 23, 24 and 34. At the other end of the shaft 84, a coupling 88 effects a disengageable connection with a fourth pump 89 that in this instance is connected to drive the motor 33. Each pump is connected to its respective motor by a separate hydraulic system including a pair of hydraulic lines 91 that pass through a control valve 92. Where the lines cross from the power unit 40 to the distributor unit 38 they are of exible material and are provided with quick disconnecting couplings 93. The control valves 92 are indicated diagrammatically in the drawing on the respective hydraulic lines but they are actually all mounted in the console 51 for convenient manipulation by the machine operator.

By this arrangement, if plastic concrete is being fed into the machine as indicated in FIG. 1 from a transit mixer or similar hauling vehicle V that discharges only into the feeding hopper 28 at the far side of the machine, the feeding hopper 27 will not be used. When only the feeding hopper 2S is being used, the other hopper 27 does not require power and its driving pump 89 may be disconnected by disengaging the coupling 88. The three pumps 87 will then operate the motor 34 driving the feeding screw 32 in the hopper 28 and the two motors 23 and 24 driving the distributing screws 21 and 22. In the event that instead of charging into the hopper 28, the feeding hopper 27 is being used as indicated in FIG. 2, the conduit connections at the pumps can be changed readily to provide for driving the hydraulic motor 33 from one of the three pumps 87 instead of from the pump 89.

When the concrete is being delivered from both sides of the slab site, the coupling 88 is engaged and all four pumps arel utilized to drive the four screws respectively. Since each pump is controlled by an independent valve 92, each motor may be started and stopped and operated in either direction selectively and entirely independently of the other motors. It is to be understood that the hydraulic system includes the usual uid supply tank (not shown) to which the several pumps are connected through the various control valves 92 in a well-known manner. When the two units 38 and 40 of the combined machine are being prepared for transportation, the disconnecting couplings 93 in the exible conduits 9,1 are all uncoupled to permit separation of the two sections.

Since all of the four screw driving motors are interchangeable and likewise all of the four pumps are interchangeable, it is possible to provide for continued operation of the machine should any one of the pumps and/ or any one of the motors become disabled. In that event the other motors may be shifted about and/or the pumps reconnected to enable the machine to continue operating although it will then be capable of receiving concrete from only one side of the slab site. For example, if one of the two motors 23 or 24 driving the two distributor screws should require repair, it may be replaced with either the motor 33 or the motor 34 taken from one of the feeding hoppers. The machine then can continue to operate, the concrete being fed only into the other feeding hopper until the disabled motor can be repaired or replaced.

The power unit 40 is furthermore provided with the usual pump (not shown) that is driven by the engine 43 for supplying hydraulic pressure to various other hydraulically operated and controlled apparatus in the usual manner.

The transverse distributing hopper or trough 20 constitutes in effect the main frame or backbone tying together the feeder troughs 27 and 28 to form the distributing section 3S of the placing machine. In order that the machine may be extensible as previously indicated, the distributing trough 20 is made up of telescoping sections. As best shown in FIGS. 2 and 6, the trough or box 20 is constituted by a central section 96 to which is slideably fitted extensions or end sections 97 and 98 that are connected at their outer ends to the feeder troughs 27 and 28 respectively. Where the central section and the end sections overlap, they are provided with lines of matching bolt holes 99 preferably spaced at six inch intervals. By sliding the end sections 97 and 98 along the central section 96, the width of the machine may be adjusted by six inch increments throughout the full range of adustment. After the adjustment has been effected and the bolt holes in the overlapping areas brought into alignment, coupling bolts 100 are passed through the aligned holes and tightened to clamp the sections together in a manner to form a rigid unitary transverse beam member spanning the distance between the side forms F.

When thus bolted together, the transverse hopper or box 20 is constituted essentially by a fixed rear or back wall 101 and a cooperating relatively movable front wall 102 that forms a clamshell type gate or movable jaw to provide for opening the trough along the bottom selectively in order to discharge plastic concrete onto the base B.

As may lbe seen best in FIGS. 4 and 5, the back wall 101 of the hopper 20 is formed in its upper part as a substantially vertical plate. At its upper edge the vertical rear wal'l plate is bent rearwardly and then downwardly to form a top beam ange whereby the back wall constitutes in effect a transverse structural beam forming the principal element of the main frame of the distributing unit 38. In its lower portion, the back wall 101 is bent forwardly to slope downwardly and forwardly at an obtuse angle with its lower edge constituting a horizontal di-scharge lip 103. The lower edge of the plate that forms the discharge lip 103 is positioned about ive inches above the level of the forms F in order to provide adequate room for the discharge of concrete thereunder when the following strike-off member 27 is adjusted to form a crown in the center of the slab being laid. As may be seen in FIG. 6, the respective ends of the back wall 101 are provided with flanges each of which is secured by bolts 104 to the adjacent feeding hopper 27 or 28.

The forward wall 102 of the trough 20 that forms the movable jaw of the clamshell hopper is spaced forwardly from the back Wall and is constituted by a plate that is disposed more or `less vertically in its upper portion and that is bent at its ltop edge to extend forwardly and then downwardly to provide a stiffening upper beam ange. The lower portion of the front wall plate is bent rearwardly to slope downwardly at an obtuse angle in such 1 1 manner that its lower edge or lip 105 engages the discharge lip 103 of the back wall when the clamshell is in closed position as shown in the drawing. The front wall 102 is provided on its outer forward surface with a series of spaced, vertically disposed reinforcing elements 106 that serve to prevent bending of the wall plate when subjected to the weight of a load of concrete in the hopper 20.

Along its upper edge, the front wall 102 is provided with a series of spaced rearwardlyextending pivot arms 107, the arms each being preferably secured to the top ange of the front wall plate in alignment with the top of one of the vertical reinforcing members 106. In the particular machine shown, four of the pivot or hinge arms 107 are utilized, the center two of the arms being in the region of the central section 96 of the trough 20 while the outer arms 107 are at the outer ends of the extensible end sections 97 and 98 respectively, as may best be seen in FIG. 2.

As appears in FIGS. 4 .and 5, each of the hinge arms 107 extends rearwardly over the trough 20 to a position slightly to the rear of the discharge lip 103 of the back wall 101. At their distal ends, the pivot arms 107 are hingedly connected |by axially aligned horizontal pivot pins 108 to a series of forwardly projecting brackets 109, respectively, each of which is secured to the top flange of the back wall 101. With the front wall pivoted in this manner upon a horizontal axis disposed rearwardly of a vertical plane represented by the broken line 110 in FIGS. 4 and 5 through the discharge lip 103, when the front wall or jaw 102 is moved toward open position by pivoting it upon the pins 108 its lower lip 105 moves upwardly as well as forwardly thereby lifting above the level of the discharge lip 103 as it moves away to permit the concrete to discharge from the hopper in a downward and forward direction. Furthermore, this upward movement of the front wall keeps its inwardly sloping lower portion close to the distributing screws to facilitate movement of the concrete along the hopper 20.

This clamshell action provides a longitudinal discharge opening i-n the bottom of t-he transverse distributing hopper of sufficient width for discharging concrete onto the base B as rapidly as required in forming the slab S. In this machine the discharge opening thus provided between the fixed discharge lip 103 and the cooperating movable lip 105 may be as much as fourteen inches. The width of the opening is under the control of the machine operator and it has been found that under most circumstances an Iopening considerably narrower than the full width is sufficient to provide for controlled discharging of the concrete as rapidly as it may be required to form the slab S as the machine advances.

Movement of the front wall 102 in opening the clamshell gate is effected by power through operation of a pair of hydraulic actuators 111, one actuator being arranged at each end of the hopper 20. As shown in FIG. 5, each actuator includes a double acting cylinder 112 that is pivotally suspended at its closed upper end from the interior `of the adjacent pusher arm 53 or 54 that extends over the end of the hopper. A piston rod 113 extending downward from the lower end of the cylinder 112 is pivotally connected at its lower end to a bracket 114 that projects forwardly from the lower portion of the front wall 102 near its end adjacent to the feeding hopper.

Hydraulic pressure for operating the two actuators 111 at the respective ends of the front wall 102 is derived through the control console 51 from the fluid pressure pump that is driven by the engine 43 in the usual manner, as previously indicated. By actuating appropriate valves on the console 51, the machine operator may raise or lower the front jaw member 102 to open or close the hopper 20 in a well-known manner. The hydraulic control system is preferably so arranged that when the clamshell hopper is opened to provide a discharge opening of desired width the jaw gate may be locked in its adjusted 12 position by preventing ow of hydraulic fluid to or from the cylinder 112 thereby retaining the adjustment.

The transverse distributing screws 21 and 22 each extend outward beyond the ends of the distributing hopper 20 into complementary hopper extension elements 121 that are formed within the feeder hopper structures 27 and 28 and that are closed at the bottom but open at the inner side for discharging into the end of the' hopper 20. Within the hopper extensions 121 the shaft of each transverse screw 21 and 22 is connected at its outer end by a detachable coupling 122 to the inner end of a stub shaft 123 that extends through and is journalled in the outer wall of the associated feeding hopper. The outer end of the stub shaft 123 carries the sprocket 82 that serves to drive the screw, the arrangement being such that by disconnecting the coupling 122 the transverse screw may be uncoupled from its supporting stub shaft 123 to provide for dismantling the apparatus when necessary.

At its inner end, each of the screws 21 and 22 is journalled in a self-aligning bearing 125, the bearings being carried by a bracket 126 that projects forwardly from the back wall 1011 of the trough 20 at the center of tthe central section 96. The central bearings receive the ends of screw shafts 127 that are telescopically fitted within the shafts of the screws 21 and 2-2 to provide for widening of the machine. When the machine is widened and the shafts 27 drawn out of the screws, additional screw flights may be clamped to the shafts 12-7 to lengthen the screws in a well-known manner.

As best shown in FIGS. 4, 5 and 6, the back wall 101 of the distributing box 20 is provided on its rear or outer surface with spaced vertically disposed reinforcing members 131. At their lower ends, the vertical members are connected to a fiat horizontal reinforcing beam 132 that extends transversely along the back of the hopper 20 and that operates also to reinforce and support the adjustable strike-off member 26.

The strike-off member 26 is extensible with the trough 20 and for this purpose it is provided with a central section that is associated with lthe central section 96 of the trough. As best shown in FIG. 6, the central section of the strike-off member 26 is divided at the midpoint of the hopper 20 into two hingedly connected elements 133 and 134 in order to provide for dellecting the strike-off member 26 at the center to form a crown on the highway slab being deposited las hereinafter described in greater detail. End sections 135 of the strike-off 26 are telescopically fitted on the ends of the central sections 133- and 134 and are associated respectively with the end sections 97 and 98 of the trough 20.

As shown in FIGS. 4 and 5, each of the two hingedly connected half sections of the strike-olf member 26 is constituted by a plate presenting a forward surface 1411 that is disposed adjacent to and parallel with the forwardly inclined lower portion of the fixed back wall 101 of the hopper. At its lower end, the plate 140 is bent rearwardly to form a horizontal screed surface 14,2. The forward surface 14'1 of the plates operates as a bulldozer to strike off the plastic concrete flowing down 4over the discharge lip 103 of the hopper 20 at a desired elevation depending upon the adjustment of the strike-off member 26. The rearwardly extending horizontal screed surface 142 tends to smooth the top of the slab at the elevation struck or by the forward surface 141 and is of suflicient width to prevent the deposited concrete from surging up ward behind the strike-off 26 as the result of hydrostatic pressure imposed by the downwardly flowing plastic concrete in the hopper 20.

To provide sufficient forward thrust for striking off the plastic concrete, the horizontal reinforcing beam 132 is equipped at spaced intervals along the strike-off 25 with forwardly projecting brackets 144 each of which carries at its forward end a roller 145 that bears against the back of the plate 140 behind the strike-off portion 141 of the strike-off element 26. The lrollers 145 push the strike-off 13 plate 140 into the plastic concrete in the manner of a bulldozer blade while also providing for vertical sliding movement of the strike-off member 26 in effecting adjustments thereof.

As previously mentioned, the discharge lip 103 of the distributing trough is in this machine spaced about five inches above the level of the forms F. As shown in FIGS. 4 and 5, the screed 142 forming the bottom of the strike-off 26 has been elevated to a position at the level of the discharge lip 103. The adjusting arrangement for the strike-off 26 is such that when laying the usual slab in one course, the strike-off may be moved downward five inches to the tops of the forms F and may be deflected upward at its center as much as three inches or more to form a crown at the center of the slab. Furthermore, when laying concrete pavement in two courses, the strike-off 26 may be moved downward a further amount to the extent of about four inches below the tops of the forms F for striking off the first course at a selected elevation adapted to position reinforcing mesh.

When operating at any selected elevation, the strike-off mechanism 26 serves to meter the flow of concrete from the distributing box and also acts as an extrusion plate to mold the top surface of the slab to the desired contour at the required elevation. Although the usual crown provided in the center of the slab is ordinarily about three inches in height, the strike-olf apparatus can be adjusted to provide a crown of ve or six inches in height if this is required. Furthermore, the strike-off 26 can be redesigned readily to provide for striking off the slab at either a higher or a lowe-r elevation than has been shown and described herein.

As indicated in FIG. 6 of the drawing, each end of the strike-off member 26 is provided with an adjusting hand wheel 148 and another hand wheel 149 is provided at the center of the strike-off fo-r effecting adjustment of the crowning action. The respective hand wheels 148 and `149 are mounted on the upper ends of threaded shafts 151 which operate in complementary nuts 152. The threaded nuts 152 are pivotally mounted at the forward ends of actuating a-rms 153 projecting forwardly from a torque shaft 154 that is journalled in bearings 155 supported on the rear edges of the vertical reinforcing plates 131 at the back of the hopper 20.

The lower ends of the two threaded shafts 151 at the respective ends of the strike-off 26 are connected by rotary swivel joints 156 to the upper edge of the plate 140 that constitutes the forward surface 141 of the strike-off member 26. When the hand wheels 148 are turned to rotate the threaded shafts 151 in the nuts 152, the respective ends of the strike-off plate 140 may be raised or lowered as desired to adjust the exact position of the strike-olf 26 relative to the slab defining forms F, both ends of the screed being ordinarily adjusted to substantially the same elevation. The lower end of the threaded shaft 151 at the center of the strike-off 26 is connected to the upper edge of one of the pla-tes 140 in the region of the hinged connection between them. When the center hand Wheel 149 is turned, the hingedly connected central section of the two screed halves 133 and 134 may be adjusted upwardly to a position higher than the ends of the screed l thereby providing for forming a peaked crown upon the vpavement slab of selected height.

When it is desired to raise or lower the strike-olf member 26 bodily without changing its crown adjustment, the three threaded shafts 151 may be lifted simultaneously through operation of the actuating arms 153 by turning the torque shaft 154. This is accomplished by means of two hydraulicv actuators 158 that are suspended from brackets 159 that project rearwardly from the top flange of the rear hopper wall 101 in alignment with the respective pivot arms 108 on the central section 96 of the trough 20. Piston rods 161 depending from the actuators 158 .are pivotally connected at their lower ends to actuating l 4 arms 162 xed on and projecting forwardly from the torque shaft 154 as best shown in FIG. 4.

Hydraulic pressure may be admitted to both of the actuators 158 through operation of valves in the console 51 in a well-known manner to extend or retract the piston rods 161 simultaneously thereby turning the shaft 154 to lower or raise the strike-off 26 for moving it between its various operating and nonoperating positions. After the strike-off 26 'has been moved bodily to a selected operating position by the hydraulic actuators, the hand wheels 148 and 149 may be turned manually as required to effect and maintain precise adjustment of the ends and center of the screed element 142. If desired, similar hydraulic actuators rnay be substituted for the hand wheels 148 and 149 and their associated mechanism in order that all positioning .and crowning adjustments of the strikeoff may be accomplished by remote control from the console 51.

A gauge bar 164 is connected and extends upward from the upper edges of the strike-off plates at each end of the strike-olf 26 and at its center as indicated in FIGS. 4 and 6 of the drawing. Each gauge bar 164 is provided at its upper end with indicia 165 which cooperate with a pointer 166 fixed on the flange of the back wall 101 of the distributing trough. By reading the indicia 165 against the pointer 166, the position of each end and of the central section of the screed may be ascertained to serve as a guide in adjusting the screed elevation and the extent of the crown for forming the slab as desired.

As previously indicated, each of the feeding hoppers 27 and 28 is secured to a flange on the associated end of the back wall 101 of the transverse distributing box 20 by means of ya series of bolts 104. The two feeding hoppers 27 and 28 are symmetrical in construction, each presenting an inner wall plate 170 through which the bolts 104 extend to secure the feeding hoppers to the transverse hopper wall 101. Each side plate 170 is provided with a large opening 171 in alignment with the transverse hopper 20 as best shown in FIG. 6 in connection with the feeding hopper 27. The opening 171 is of suicient size to admit the end of the associated distributing screw 21 and constitutes a passageway for concrete moving from the hopper extension area 121 into the distributing trough 20. The distributing hopper extension 121 forms the closed discharge end of the feeding hopper 27, for example, the distributing trough 20 being open at the bottom to place the concrete on the base B.

The other or outer side of each feeding hopper is constituted by an outer side plate 172 lthat is somewhat lower than the inner side plate 170 to facilitate charging the hopper from the outer side of the machine. As may be seen best in FIG. 13, the bottom of the hopper is constituted by a plate 173 that is bent upwardly at each side to join the lower edges of the the side plates 170 and 172 thereby forming a trough in which the screw 31 operates. The upper edge of the hopper 27 is ared outwardly as shown in the drawing to receive the plastic concrete and above the screw the hopper is provided with a guard grill or grate 174 as a safety measure.

The strut 70 which extends downward to carry the bogie truck 29 serves also as a reinforcing member that stiffens the bottom plate 173 of the hopper in supporting the weight of the concrete. The associated pusher arm 53 is connected to and extends rearwardly primarily from the inner side plate 170 of the hopper. The forward end of each feeding hopper is closed by a front plate 176 that serves also to support the drive mechanism for the feeding screw and the bearing for the front end of the screw shaft. The other end of the screw shaft is journalled in a transverse brace or bracket 177 extending from side to side near the forward side of the distributing hopper extension 121.

As best shown in FIG. 3, the upper part of the outer side plate 172 of each feeding hopper is constituted by a removable section 179 that is secured atits ends to the 15 ends of the hopper by bolts 180. Upon removing the bolts 180, the side pieces 179 may be detached in order that the outer side wall 172 may be reduced in height to better accommodate certain types of hauling vehicles that may be used to charge the hopper with plastic concrete.

The two screws 31 and 32 in the feeding hoppers 27 and 28 are right hand and left hand respectively in order that when feeding concrete rearwardly they turn in the proper direction -to facilitate the fiow of concrete inwardly through the opening 171 into the distributing trough 20. In the event that the placing machine is to be used for paving operations in which material is to be delivered to the machine along only one side of the base B, the machine may be equipped with only one feeding screw and its associated driving mechanism on the side of the machine that is to receive the concrete.

Each of the feeding hoppers 27 and 28 is arranged to be removed readily in order to reduce the size of the distributing section 38 for transportation from one to another job site, as previously mentioned. For this purpose, the forward part of each feeding hopper is connected to the rearward part or distributing hopper extension 121 by a series of removable bolts 181 that pass through matching fianges on the respective hopper parts. After the distributing section 38 has been disconnected from the power section 40, the bolts 181 may be removed and the forward parts of the feeding hoppers 27 and 28 detached. As shown, the bolted flanges are disposed just rearwardly of the transverse bracket 177 that carries the rearward end of the feed screw shaft. By this arrangement, when the forward parts are removed the feed screws are carried with them in their bearings and likewise the transverse screws remain in their bearings within the transverse part of the distributing section.

The charging area presented at the top of each of the feeding hoppers 27 and 28 is approximately twelve feet long. When laying a pavement the placing machine travels along the forms F at a substantially constant, slow speed as it places the concrete continuously upon the base B. Likewise, the plastic paving material being placed is charged into one or both of the feeding hoppers, more or less continuously. To this end, successive hauling vehicles such as the vehicle V, may be spotted at the side of the paving site as shown in FIG. 1 in position to discharge into the forward end of the feeding hopper. As the plastic concrete is charged into the hopper, the placing machine continues its forward movement relative to the stationary vehicle V. The feeding hopper, however, is of such length that the entire load of the hauling vehicle V may be discharged into the hopper while the placer is moving forward relative to the parked vehicle without the necessity of changing the position of the vehicle. When the empty vehicle moves away, another hauling vehicle V is brought into position to discharge into the forwar-d end of the hopper and the operation continued with the plastic concrete being fed into either hopper or into both hoppers simultaneously as may be convenient. In this manner, the paving material may be delivered to the placing machine as rapidly as the hauling vehicles can be discharged into the hoppers 27 and 28, the forward travel of the machine being limited only by the rate at which the paving material can be delivered to it and dumped into the feeding hoppers.

As previously mentioned, the feeding screws 31 and 32 move the material rearwardly and inwardly into the transverse hopper extensions 121 in the ends of the feeding hoppers and through the openings 171 with the distributing screws 21 and 22 carrying the material along the transverse hopper 20. The action of the screws in moving the plastic concrete operates to remix the material and thereby overcomes any segregation of ingredients that may have occurred in the material while being transported in the hauling vehicle. As rapidly as the material is moved from the hopper extension 121 through the opening 171 into the distributing hopper 20, it is spread 1S transversely of the site and at the same` time flows downward through the open bottom of the hopper onto the base B. Through proper operation of the distributing screws 21 and 22, the material iiowing downward through the hopper Ztl may be maintained at a substantially uniform `depth throughout the width of the slab being laid.

By maintaining the depth of the concrete in the hopper substantially constant, the weight of the material bearing down on the base B is substantially uniform at all times and, therefore, the material as it is formed into the slab S is compacted uniformly and solidifies into auniform, level homogeneous structure. Furthermore, the uniform depth of material provides a constant hydrostatic head upon the concrete being leveled by the strike-off 26 thereby avoiding surging of the plastic material behind the strike-off. While the material in the lower part of the transverse trough 20 is moving downward onto the base B, the material above it is being distributed transversely of the base and along the trough 20 by the screws 21 and 22. Since the screws are some distance above the base B, the force required to move the material transversely is not transmitted to the base in any appreciable amount but is exerted as friction upon the inner surface of the trough. Accordingly, the reaction to this force is not exerted against the forms F but rather is absorbed within the structure of the transverse trough itself. As a result, no racking forces are exerted upon the forms F when reversing the screws 21 and 22 in distributing the material transversely of the slab site.

As may best be seen -in FIG. 10, the concrete C owing down through the open bottom of the trough 20 tends to roll forwardly from the discharge opening. To control the flow of material, the movable forward wall or jaw 102 of the clamshell trough is adjusted to provide a discharge opening of a width best suited to the proper discharge of the Imaterial. Also in FIG. l0 it may be seen that the strike-off member 26 limits the iiow of material rearwardly from the hopper to the amount required to form the slab S of the desired thickness. Furthermore, the screeding surface 142 of the strike-ofi member operates to extrude the slab S onto the base B and prevents upward surging of the material flowing under the strikeoff 26.

After the plastic material has been struck off and smoothed by the screeding surface 142, it is further smoothed and finished by the operation of the transverse screed 49 and any other finishing apparatus that may be applied subsequently to smooth the traffic supporting surface of the slab. To this end, the placing machine of this invention may if desired be combined with other apparatus such as a surface finishing machine of the screed and float type as shown in FIG. 7.

The comlbined placing, transverse screeding and fioat finishing machine shown in FIG. 7 includes a finishing section 182 that is disclosed and claimed in copending application Serial No. 180,141 filed March 16, 1962, and entitled Pavement Laying and Finishing Apparatus. Through operation of this combined equipment as a unit, a slab of pavement may be completely lai-d and finished by the one machine in a single continuous traverse of the site. The finishing section 182 of the combined machine includes a relatively long framework 183 that is provided at each side with .fa forwardly extending towing arm 184. Each of the towing arms 184 is provided at its forward end with an aperture 185 that fits over a king pin 186 projecting upward from the end member of the frame 41 of the pushing unit 40. The trailing ends of the framework 183 yare supported pivotally upon tandem bogies 187 provided with forward and rear wheels 188 that run on the forms F.

As more fully explained in the copending application, the framework carries two oppositely reciprocating transverse metering screeds 191 and 192 that are adjustable to provide the desired finished shape or contour to the upper surface to the slab S. Following the second screed 192, a smoothing oat pian 193 slides over the shaped surface of the slab S and imparts to it the final contour and finish required on the trafiic supporting surface of the pavement.

In this combined laying machine, the forward distributing unit 38 may be identical with the unit hereinbefore described. The pushing power unit 40 likewise may be substantially yas previously described, with the exception that the rear screed 49 has been replaced by the two screeds 191 and 192 of the finishing unit 182 and by the a-ddition of the second king pin 186 at each side of the machine frame which provide lost motion connections with the towing arms 184 at the respective sides of the finishing unit.

In utilizing a combined machine of the type shown in FIG. 7, freshly mixed concrete in plastic condition may be dumped into one or the other of the feeding hoppers 27 and 28 from a transportation vehicle V which is shown in the drawing in the form of the usual rear opening dump truck. The plastic concrete is then distributed and placed upon the base B from the transverse hopper 20 and struck off to the desired elevation and approximate shape by the adjustable strike-off 26. The two reciprocating screeds 191 and 192 then finish the upper surface of the slab to the `desired contour whereupon the fioat plate 193 smooths the surface and leaves it in finished condition for solidifying in the required shape without any further finishing operation.

Although the placing machine as shown in FIGS. l through 7 is arranged for operation upon the forms F defining the sides of the slab, the apparatus also is applicable to paving equipment of the slip-form type. As shown in FIG. 8, a slip-form paver 195 provided with forwardly projecting side forms or slip-form beams 196 is arranged to carry the spreading unit 38 as an integral part of the machine. As indicated in the dnawing, the transverse distri-buting hopper 20 extends from one to the -other of the slip-form beams 196 and is supported upon them.

From the respective ends of the hopper 20, the feeding hoppers 27 and 28 project forwardly along and are secured to the forward parts of the respective slip-form beams 196. Treads or tracks 197 operating around the beams from end to end in a well-known manner provide for advancing the machine along the site being paved. Plastic concrete charged into either of the feeding hoppers is placed by the transverse hopper 20 upon the base B between the slip-forms 196. As the machine advances, the slip-forms 196 shape the edges of the slab while the surface thereof is shaped by the forming plate of the slipform paver 195 in the usual manner. Trailing forms 198 are towed behind the paver to maintain the edges of the slab while they are solidifying. By utilizing this machine, the plastic concrete is properly distributed and molded into the form of a monolithic pavement slab in a single operation and without the necessity of providing temporary side forms.

As shown in FIG. 9 of the drawing, the distributing apparatus of this invention may be integrated somewhat more completely into a slip-form paver combination. As there shown, a modified slip-form paver 201 is provided with relatively high side elements or plates 202 that constitute the slip-forms and that are shaped to carry the crawler tracks 197 at an elevation higher than the transverse trough 20. By this arrangement the trough 20 is extended on each side of the machine through openings in the side forms 202.

This permits the charging hoppers 27 and 28 to be mounted on the outer sides of the side forms 202 communication being had through the openings therein with the ends of the distributing trough. The machine is thereby made somewhat more compact ibut operates in the same manner in that material fed into the charging hoppers flows from them through the openings in the side forms 202 and is distributed by the transverse conveyor. The extrusion plate of the paver 201 then molds the top surface and the side edges of the monolithic slab S in the usual manner, leaving it ready for use as soon as it solidifies.

The combined placer and slip-form machines shown in FIGS. 8 and 9 may be equipped with reinforcing mesh laying arrangements as shown in FIGS. 10 and l1, the mesh layer shown being applicable as well t-o the other machines that operate on the forms F. As previously indicated, reinforcing mesh is usually incorporated in a pavement slab by laying a first course of concrete, then placing the mats of mesh on top of the first course after which a second or top course of concrete is laid over the mesh and bonded to the first course. In the apparatus shown Vin FIGS. 10 and l1, the reinforcing mesh is embedded in the plastic concrete at a position within the pavement slab at the proper elevation above the base as the monolithic slab is being formed by the .placer of this invention in a single continuous operation.

To this end, steel reinforcing mesh M is laid on the sub-base B ahead of the placing machine as indicated in FIG. 10, individual mats or sections of the mesh being secured together to form a continuous ribbon or strip of mesh. If dowel chairs are to be used for expansion joints I, they are placed on the base B first and the mesh M then laid loosely over them. As the placing machine advances, a mesh elevating bridge 205 extending between the feeding hopper 27 and 28, slides under the mesh M in a manner to lift it lfrom the base B to an elevation considerably higher than the elevation at which it is to be embedded within the slab S. As shown in FIGS. 10 `and ll, the elevating bridge 205 is high enough to pass over the d-owel chair joints I and is `constituted by a pair of spaced transverse beams 206 that are secured at their respective ends at the inner sides of the feeding hoppers 27 and 28 thereby serving also to brace each hopper against the other for the purpose of stabilizing the forward end 0f the placing machine.

Longitudinally disposed mesh elevating runners 207 .are secured to the transverse beams 206 at spaced intervals therealong transversely of the base B as shown in FIG. 11. The runners or lifts 207 are curved downwardly at their forward ends as shown in FIG. 10 t0 engage beneath and guide the mesh M being lifted lfrom the base B. At their trailing ends, the elevator runners 207 are provided with rearwardly extending lifting fingers 208 that are preferably of tempered spring steel and that eX- tend back beneath the distributing hopper 20. As best shown in FIG. l0, the mesh lifting fingers 208 support the mesh M in its elevated position but somewhat below the level of the top of the slab S. With the mesh thus supported the plastic concrete C discharging out of the trough 20 flows downwardly and forwardly through the elevated mesh onto the base B. This results in the mesh being embedded within the plastic concrete at an elevation somewhat higher than its preferred final position in the slab S.

To position the mesh M precisely in the slab, there is provided a series of depressor fingers 209 that are fastened beneath and extend forwardly from the screed surface 142 of the adjustable strike-off member 26. As shown in FIG. l0, the depressor fingers 209 are turned up at their forward ends to engage and ride over the mesh M in the region of the trailing ends of ,the cantilevered -mesh lifting fingers 208. As the mesh M becomes embedded in the downwardly flowing concrete C, the upturned mesh depressor fingers 209 in riding over it press it down gradually into the plastic concrete to the precise level which it is to assume within the slab S to provide the optimum reinforcing effect.

When the concrete C flows down through the mesh M small voids may be left below each wire of the mesh, but since the mesh is moved downward by the depressor fingers 209 to its final position, these voids are closed and the wires of the mesh are solidly embedded in the concrete. Whatever voids may occur above the mesh wires and behind the depressor fingers 209 are closed by the extrusion meter action of the screed plate element 142 that extends rearwardly from the forward face plate 140 of the strike-offkelement 26. To assist in this finishing operation, the screed plate 142 may be provided with a vibrator 211 that operates in a well-known manner to fiuidize the concrete and close the voids in its upper surface. This results then in the mesh M being placed at a precise elevation within the slab S and completely embedded within the plastic material in a manner to remain in its proper position as the material solidies thereby to afford maximum reinforcement and unified structural strength to the monolithic slab.

" Although the placing machine of this invention has been shown and described as equipped with feeding hoppers 27 .and 28 that extend forwardly along the sides of the base B, under some circumstances it may be more desirable to extend the feeding hoppers laterally. In the modified form of the invention shown in FIG. 12, a laterally extending feeding hopper 217 is shown projecting outward from the machine in position to receive the plastic paving material C from a hauling vehicle V positioned parallel with and outside of the forms F. The outwardly projecting feeding hopper 217 is pivotally connected by hinges 218 to the outer surface of a side plate or frame member 219 that takes the place of the longitudinally feeding hopper previously described.

In operation, the feeding hopper 217 first may be folded upward to a vertical position upon the hinges 218 whereupon the vehicle V may be driven along the side of the site past the placing machine and spotted at a position rearwardly of the hopper 217. The feeding hopper 217 then may be lowered behind the vehicle V to its horizontal outwardly projecting position, whereupon the concrete C may be dumped from the rear of the vehicle into the hopper 217. Upward pivoting movement of hopper 217 is effected by means of a hydraulic actuator including a cylinder 221 that is pivotally connected to its closed end to a bracket 222 on the back wall 101 of the distributing hopper 20. A piston rod 223 projecting from the other end of the cylinder 211 is pivotally connected at its outer end to a bell crank arm 224 extending upward from the hopper 217. When pressure fiuid is admitted to the cylinder 221 in a manner to retract the piston rod 223, the crank arm 224 operates to pivot the hopper 217 upward on its hinges 218 to its vertical position.

When the feeding hopper 217 is in its lowered outwardly projecting position it is in axial alignment with the distributing hopper 20 and communicates with it through an opening 226 in the side plate 219. The hopper 217 is provided with a feeding screw 227 that is disposed in axial alignment with the distributing screw 21 and in effect constitutes an extension of it. Driving mechanism 229 that is mounted on the rearward side of the hopper 217 is connected by a shaft 2.31 to a speed re-ducer 232 at the outer end of the hopper 217 by means of which power is transmitted to the outer end of the screw 227. Since the driving mechanism for the screw 227 is all mounted on the hopper 217 it moves with the hopper when tilted to its vertical position and does not need to be disconnected.

The driving mechanism for the feeding screw 227 operates also to drive the adjacent distributing screw 21 through connection therewith by means of a positive clutch (not shown). The positive clutch disconnects in the usual manner when the hopper 217 is pivoted upward and the driving connection is reestablished when the hopper is in its Vlowered position with the screws in axial alignment. By this arrangement, rear dumping hauling veh-icles may be operated along the shoulder of the slab being laid and dumped successively into the trough 2.17 upon it being lowered in turn behind each vehicle. Accordin-gly, the hauling vehicles all may proceed in the same direction without the necessity of turning or other maneuvering.

From the foregoing description of apparatus exemplifying pavement material placing equipment embodying the present invention and the accompanying explanation of the manner in which it operates, it will be apparent that a new and improved arrangement has been provided by this invention for distributing and placing plastic paving material to form a monolithic pavement slab in a single continuous operation This improved result is achieved by providing placing apparatus that is arranged to receive a full load of freshly mixed concrete poured rapidly from a hauling vehicle while simultaneously distributing it quickly across the site being paved. By this means, a hea-Vy load of material may be placed so rap-idly that its weight is never concentrated entirely on one side of the machine and its supporting forms. Furthermore, the material is distributed uniformly across the paving site in such a manner that it is evenly compacte-d upon the base and solidifies evenly and smoothly.

Although specific examples of paving material distributing and placing machines have been set forth herein by way of a full disclosure of practical and useful embodiments of the invention', it is to be understood that the improved features disclosed herein may be incorporated in somewhat different apparatus by those familiar with the art of pavement laying without departing from the spirit and scope of this invention as defined in the subjoined claims.

The novel features of the invention having now been fully set forth and explained, I claim as my invention:

1. In apparatus for distributing and placing newly mixed concrete in plastic condition to form a slab of pavement, a framework adapted to extend over and to be advanced alon-g the site of a pavement slab being laid, a distributing trough for concrete carried by said framework in position to extend transversely of the slab site and provided along the bottom thereof with an adjustable concrete discharging opening, two conveyor screws arranged in end-to-end alignment within said distributing trough for moving concrete therealo-ng, driving means operatively connected to each of said conveyor screws in manner to drive each screw independently in either vdirection selec-tively, a feeding trough connected to and extending forwardly from each end of said distributing trough, a feeding screw arranged within each of said feeding troughs for moving concrete deposited therein into said distributing trough, driving means operatively connected t-o each of said feeding screws in manner to drive each screw independently and selectively, and an adjustable strike-off member carried by said framework behind and closely adjacent to said distributing trough in position to enga-ge and strike off the plastic concrete discharged from the bottom of said distributing trough through said adjustable concrete discharging opening, the arrangement being such that concrete may be charged into either or both of said feeding troughs as said apparatus advances along the site being paved and fed therefrom into said distributing trough for prompt placement upon the site the deposite-d concrete then being leveled by said strikeoff Vmem-ber to form the slab of pavement.

2. In a placer for laying a slab of concrete pavement in plastic condition continuously and progressively, a transverse distributing trough arranged to discharge a 'ribbon of plastic concrete onto the site being paved as theA placer travels along the site, a wheel disposed at each end of said transverse trough for movably supporting it at the respective edges of the site being paved, resilient force limiting means' arranged to connect each of said wheels to one end of said trough respectively to support said trough thereon resiliently, a feeding trough extending forwardly fro-m each end o-f said transverse trough and arranged to feed plastic concrete into said transverse trough, .a tandem bogie having two wheels arranged under each of said forwardly extending feeding troughs to support yit for movement, a pushing arm extending rearwardly 'from each of said feeding troughs, a power unit including 21 a rectangular frame disposed transversely of the site being paved and arranged behind said transverse distributing trough with its respective ends beneath the distal ends of said rearwardly extend-ing pushing arms, means on the respective ends of said power unit frame disposed to engage and push against the distal ends of said arms, and two wheels disposed at each end of said power un-it frame in tandem relationship and mounted thereon in manner to support said power unit for movement along the site, the arrangement being such that when plastic concrete is poured into said feeding troughs and feed therefrom into said distrib-uting trough the weight thereof is sustained by said tandem bogies and by said resiliently mounted wheels until the weight on said wheels exceeds the sustaining capacity of said force limiting resilient connecting means whereupon said troughs settle downward sufficiently to cause said overlying distal ends of said rearwardly extending pushing arms to bear down upon the respect-ive ends of said power unit frame and thereby transfer some of the weight thereto which is then sustained by the two wheels at each end of said power unit, whereby the weight of ,the load of concrete in said troughs is thereby distributed among live wheels spaced along each side of said placer.

3. In a concrete placing machine for distributing freshly mixed concrete in plastic condition upon a site to form a slab of pavement, a framework adapted to span and arranged to advance along the site of the pavement slab being formed, a transverse concrete distributing trough carried by said framework and having a discharge opening along its lower surface positioned to deposit concrete onto the site t-o form the slab, two conveyor screws arranged in end-to-end relationship within said trough for distributing plastic concrete therealong, a longitudinal lfeeder trough carried by said framework land extending forwardly from and connected to each end of said transverse distributing trough, a feeding conveyor screw arranged within each of said feeder troughs for feeding plastic concrete therealong into the associated end of the distributing trough, an hydraulic motor for driving each of said feeding and distributing screws, power transmission mechanism interconnected between each hydraulic motor and its associated conveyor screw to drive it, an hydraulic pump for driving each of said hydraulic motors, fluid pressure transmitting and control apparatus interconnecting each of said hydraulic pumps individually with its associated hydraulic motor to drive it, a source of power mounted on said framework, and driving mechanism interconnecting said source of power and said hydraulic pumps to drive them, the arrangement -being such that each of said feeding and distributing conveyor screws is driven a-nd controlled by a wholly independent hydraulic power transmission system.

4. In apparatus for placing concrete in plastic condition to form a pavement slab, a transverse trough-like distributing hopper adapted to span the site of a slab being laid and arranged to open at the bottom for discharging concrete, .a longitudinal feeding hopper connected to and extending forwardly from each end of said distributing hopper in manner to feed concrete into said distributing hopper, two conveyor transfer screws disposed end to end in said distributing hopper and operative therein in manner to distribute concrete therealong, a conveyor transfer screw disposed in each of said longitudinal feeding hoppers for feeding concrete therefrom into said distributing hopper, an hydraulically opera-ted motor arranged to drive each of said conveyor screws independently, a speed reducing mechanism connected between each of said hydraulic motors and the associated conveyor screw driven thereby in manner to drive the screw at reduced speed, a source of power for driving said motors and screws, three hydraulic pumps connected t-o said source of power in manner to be driven thereby, separate hydraulic conduit systems connecting said three pumps respectively to the two said motors driving said distributing screws and one of said motors driving one of said feeding screws, a fourth hydraulic pump, a separate conduit system connecting said fourth pump to the other of said motors driving the other of said feeding screws, and a disconnectable coupling selectively connecting said fourth hydraulic pump to said source of power, the arrangement being such that when concrete is being delivered to only the rst of said feeding hoppers, said coupling may Vbe disconnected to uncouple said fourth pump from said source of power.

5. In a machine for laying plastic concrete to form a pavement slab, a frame adapted to span and to travel along the site of a slab of pavement being laid, a transverse placement hopper carried by said frame in position to span and to discharge plastic concrete on to the site, two transfer screws arranged transversely end to end within said placement hopper for distributing concrete therealong, a longitudinal feeding hopper extending forwardly from and connected to each end of said transverse placement hopper for receiving plastic concrete, feeding screws arranged longitudinally in each of said feeding hoppers for feeding con-crete into the ends of said transverse placement hopper, an hydraulic system including a motor connected to and arranged to drive each of said distributing screws and each of said feeding screws individually all of said four motors being similar and interchangeable, a source of power mounted -on said frame, four hydraulic pumps operatively connected to said source of power in a manner to be driven thereby all of said four pumps likewise being similar and interchangeable, and an hydraulic control circuit interconnecting each of said four pumps individually with one of said motors respectively to drive said screws selectively and independently, the arrangement being such that should any one of said pumps or any one of 'said motors become disabled said hydraulic system may be rearranged to interchange pumps or to interchange motors as may be required to provide for driving said two distributing screws and a selected one of said feeding screws.

6. In a machine for laying reinforced concrete pavement, a transverse distributing trough open at the bottom for discharging concrete in ribbon form onto a site being paved as said trough advances along the site to form a slab of pavement, means to feed plastic concrete into said transverse `trough and to distribute the concrete along said trough transversely of the site, mesh supporting fingers projecting forwardly from said transverse trough in position to lift reinforcing mesh and to support it at an elevation somewhat higher than its normal position within the slab being formed but below the elevation of the top of the slab, said fingers serving to hold the mesh in elevated position while under said trough and while the plastic concrete flows down from said trough through the mesh onto the pavement site to embed the mesh in the slab being formed, mesh depressing fingers extending rearwardly from said transverse trough in position to depress the embedded mesh within the slab of plastic concrete to its normal desired position within the slab, and a strike-off member arranged to follow said distributing trough and operative to strike off and smooth the top surface of the plastic concrete on the pavement site above the embedded mesh to form the reinforced monolithic slab to the desired lthickness and surface contour.

7. In apparatus for placing concrete in plastic condition to lay a slab of pavement, a frame adapted to span and to travel .along a site being paved, a transverse distributing hopper arranged to open at the bottom and carried by said frame in position to discharge plastic concrete in the form of a down flowing ribbon extending across the full width of the site being paved as the apparatus travels along the site, said hopper comprising a fixed back wall element secured to said frame and extending downwardly and forwardly to terminate in a transverse discharge lip at its lower forward edge, a movable front wall spaced forwardly from said back wall at its top and extending downwardly and rearwardly to engage said discharge lip of said back wall when in closed position, a plurality of pivot arms spaced transversely of the distributing hopper, each .arm extending rearwardly from the top of said front wall, means projecting ttor- Wardly from said back Wall to which said arms are pivo-tally connected intermediate said walls, and power operated gate opening apparatus connected between said frame and said mova'ble front wall and -operative to pivot said front wall forwardly and upwardly to disengage it from said discharge lip and to open said clamshell hopper a selected predetermined distance both horizontally and vertically to provide for discharging the ribbon of plastic concrete therefrom over said discharge lip onto the site being paved.

8. In combination with apparatus as set forth in claim 7, mesh supporting members projecting forward of said hopper arranged to support the mesh while the concrete vflows from the hopper through the mesh, and means to References Cited by the Examiner UNITED STATES PATENTS Gardiner 94-46 Robb 94-46 Robb 94-46 Holter 941-22 Baker 94-46 Williams 94-44 Bohannan 94-44 Wood 94-44 Pollitz 94-46 Warren 94-46 Ytterberg 94-24 Creswell 94-44 Ross 94-46 Ekstrom 94-46 Guntert 94-44 JACOB L. NACKENOFF, Primary Examiner. 

1. IN APPARATUS FOR DISTRIBUTING AND PLACING NEWLY MIXED CONCRETE IN PLASTIC CONDITION TO FORM A SLAB OF PAVEMENT, A FRAME WORK ADAPTED TO EXTEND OVER AND TO BE ADVANCED ALONG THE SITE OF A PAVEMENT SLAB BEING LAID, A DISTRIBUTNG TROUGH FOR CONCRETE CARRIED BY SAID FRAMEWORK IN POSITION TO EXTEND TRANSVERSELY OF THE SLAB SITE AND PROVIDED ALONG THE BOTTOM THEREOF WITH AN ADJUSTABLE CONCRETE DISCHARGING OPENING, TWO CONVEYOR SCREWS ARRANGED IN END-TO-END ALIGNMENT WITHIN SAID DISTRIBUTING TROUGH FOR MOVING CONCRETE THEREALONG, DRIVING MEANS OPERATIVELY CONNECTED TO EACH OF SAID CONVEYOR SCREWS IN MANNER TO DRIVE EACH SCREW INDEPENDENTLY IN EITHER DIRECTION SELECTIVELY, A FEEDING TROUGH CONNECTED TO AND EXTENDING FORWARDLY FROM EACH END OF SAID DISTRIBUTING TROUGH, A FEEDING SCREW ARRANGED WITHIN EACH OF SAID FEEDING TROUGHS FOR MOVING CONCRETE DEPOSITED THEREIN INTO SAID DISTRIBUTING TROUGH, DRIVING MEANS OPERATIVELY CON- 